AIn the class II MHC pathway, protein antigens in the cytosol are processed by proteasomes
BIn the class I MHC pathway, extracellular protein antigens are endocytosed into vesicles and processed
CIn the class I MHC pathway, transporter associated antigen processing (TAP) protein is required for translocating processed peptides generated in the cytosol
DInvariant chain in endoplasmic reticulum is involved in transport of peptides and loading of class I MHC